System Diagrammer is installed. Open it from SYGNAL toolbox, or go to https://localhost:8050.

If it was already running, restart it from SYGNAL toolbox to use this version. Restarting stops its database and starts it again, and your drawings are kept.

To remove it later, use Uninstall System Diagrammer in SYGNAL toolbox. That keeps your data unless you choose to remove it too.